[Intel-gfx] [PATCH v4 16/19] vfio: Add VFIO_DEVICE_BIND_IOMMUFD

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu at intel.com>
> Sent: Tuesday, February 21, 2023 11:48 AM
> 
> +
> +void vfio_device_cdev_close(struct vfio_device_file *df)
> +{
> +	struct vfio_device *device = df->device;
> +
> +	mutex_lock(&device->dev_set->lock);
> +	if (!smp_load_acquire(&df->access_granted)) {

there is no contention with another one changing this flag at this
point so directly accessing it is fine.

but actually should check device->open_count as v3 does. Otherwise
the last error on copy_to_user() in ioctl_bind_iommufd() simply returns
here given df->access_granted hasn't been set but .open_device()
has been completed.